Ventricular fibrillation episodes related to managed ventricular pacing algorithm in a patient with mitral valve prolapse - "Arrhythmic MVP due to MVP".

We report a case of an implant cardiac defibrillator (ICD) patient who an ICD implanted for ventricular fibrillation (VF) related to mitral valve prolapse. He has 2 episodes of VF in his device lives. First episode of VF in year 2016 was initiated after a pause related to the MVP™ algorithm with a critically timed PVC. MVP™ was turned off which prevented further VF episodes. However, MVP™ was turned back on at the device replacement in 2018. A second VF episode developed with similar mechanism in 2021 and MVP™ was subsequently turned off with no further VF recorded. This case highlights the importance of recognizing the mechanism of initiation of tachy-arrhythmia episodes and serves as an important reminder regarding optimization of device settings at the time of replacement.

A role of flavonoids in cytochrome c-cardiolipin interactions.

The processes preceding the detachment of cytochrome c (cyt c) from the inner mitochondrial membrane in intrinsic apoptosis involve peroxidation of cardiolipin (CL) catalyzed by cyt c-CL complex. In the present work, we studied the effect of 17 dietary flavonoids on the peroxidase activity of cyt c bound to liposomes. Specifically, we explored the relationship between peroxidase activity and flavonoids' (1) potential to modulate cyt c unfolding, (2) effect on the oxidation state of heme iron, (3) membrane permeability, (4) membrane binding energy, and (5) structure. The measurements revealed that flavones, flavonols, and flavanols were the strongest, while isoflavones were the weakest inhibitors of the oxidation. Flavonoids' peroxidase inhibition activity correlated positively with their potential to suppress Trp-59 fluorescence in cyt c as well as the number of OH groups. Hydrophilic flavonoids, such as catechin, having the lowest membrane permeability and the strongest binding with phosphocholine (PC) based on the quantum chemical calculations exhibited the strongest inhibition of Amplex Red (AR) peroxidation, suggesting a membrane-protective function of flavonoids at the surface. The results of the present research specify basic principles for the design of molecules that will control the catalytic oxidation of lipids in mitochondrial membranes. These principles take into account the number of hydroxyl groups and hydrophilicity of flavonoids.

Fear effects associated with predator presence and habitat structure interact to alter herbivory on coral reefs.

Non-consumptive fear effects are an important determinant of foraging decisions by consumers across a range of ecosystems. However, how fear effects associated with the presence of predators interact with those associated with habitat structure remain unclear. Here, we used predator fish models (Plectropomus leopardus) and experimental patches of the macroalga Sargassum ilicifolium of varying densities to investigate how predator- and habitat-associated fear effects influence herbivory on coral reefs. We found the removal of macroalgal biomass (i.e. herbivory) was shaped by the interaction between predator- and habitat-associated fear effects. Rates of macroalgal removal declined with increasing macroalgal density, likely due to increased visual occlusion by denser macroalgae patches and reduced ability of herbivorous fishes to detect the predators. The presence of the predator model reduced herbivory within low macroalgal density plots, but not within medium- and high-density macroalgal plots. Our results suggest that fear effects due to predator presence were greatest at low macroalgal density, yet these effects were lost at higher densities possibly due to greater predation risk associated with habitat structure and/or the inability of herbivorous fishes to detect the predator model.

Seasonal variation of Sargassum ilicifolium (Phaeophyceae) growth on equatorial coral reefs.

Temporal and spatial variations in Sargassum ilicifolium thallus density and length were investigated on equatorial coral reefs in Singapore from November 2011 to October 2012. Thalli density varied little throughout the year, however, we found strong seasonal patterns in thallus length and identified temperature as the significant driver. Sargassum ilicifolium reached maximum length in December (110.39 ± 2.37 cm) during periods of cooler water temperatures, and minimum length in May (9.88 ± 0.48 cm) during periods of warmer water temperatures. Significant spatial variation was also observed for both thallus density and length of S. ilicifolium among reefs. Within reefs, densities of S. ilicifolium were higher on reef flats (20.40 ± 0.40 individuals · 0.25 m-2 ) compared to upper reef slopes (5.66 ± 0.23 individuals · 0.25 m-2 ). Our findings highlight that marked seasonality in the growth of canopy-forming macroalgae can occur within equatorial reef systems where temperature ranges are restricted (<3°C).

Sediment-driven plastisphere community assembly on plastic debris in tropical coastal and marine environments.

Coastal habitats have been suggested to serve as a sink for unaccounted plastic debris, i.e., "missing plastic" in the sea, and hence, a hotspot of plastic pollution in the marine and coastal environments. Although the accumulation of plastic debris may pose significant threats to coastal ecosystems, we know little about the fate of these plastic debris and their ecological impacts due to the lack of studies on plastic-microbe interactions in coastal habitats, especially for the tropical marine and coastal environments. In this study, we collected plastic debris from 14 sites consisting of various coastal ecosystems (seagrass meadows, mangrove forests, and beaches), and marine ecosystem (coral reef) around Singapore and characterized the prokaryotic and eukaryotic microbial communities colonized on them. Our results showed that the composition of plastisphere communities in these intertidal ecosystems was predominantly influenced by the sediment than by the plastic materials. Compared with surrounding sediment and seawater, the plastic debris enriched potential plastic degraders, such as Muricauda, Halomonas, and Brevundimonas. The plastic debris was also found to host taxa that play significant roles in biogeochemical cycles (e.g., cyanobacteria, Erythrobacter), hygienically relevant bacteria (e.g., Chryseobacterium, Brevundimonas), and potential pathogens that may negatively impact the health of coastal ecosystems (e.g., Thraustochytriaceae, Labyrinthulaceae, Flavobacterium). Taken together, our study provides valuable insights into the plastic-microbe interactions in tropical coastal and marine ecosystems, highlighting the urgent need for plastisphere studies to understand the fate and ecological impacts of plastic debris accumulated in coastal habitats.

Litter traps: A comparison of four marine habitats as sinks for anthropogenic marine macro-litter in Singapore.

The potential for marine litter being trapped in biodiverse marine habitats such as mangrove forests, seagrass meadows and coral reefs is poorly understood. This study presents the first comprehensive investigation on the status of macro-litter across four marine habitats in Singapore during the two monsoonal seasons. Overall, litter density did not vary considerably between the southwest and the northeast monsoon. The litter density in terms of count was generally lower in seagrass meadows and coral reefs compared to mangroves and beaches. Plastic was the major type of litter found across most habitat types. Notably, many fishing-related items were found on coral reefs, while drinking straws were abundant at the mangrove strandlines during the southwest monsoon. Foam fragments and cigarette butts were common at the beach strandlines. These results suggest that mangroves among other habitats examined here should be prioritised for clean-up efforts in order to restore these critical coastal habitats.

Chemically Mediated Interactions with Macroalgae Negatively Affect Coral Health but Induce Limited Changes in Coral Microbiomes.

Allelopathic chemicals facilitated by the direct contact of macroalgae with corals are potentially an important mechanism mediating coral-macroalgal interactions, but only a few studies have explored their impacts on coral health and microbiomes and the coral's ability to recover. We conducted a field experiment on an equatorial urbanized reef to assess the allelopathic effects of four macroalgal species (Bryopsis sp., Endosiphonia horrida, Hypnea pannosa and Lobophora challengeriae) on the health and microbiomes of three coral species (Merulina ampliata, Montipora stellata and Pocillopora acuta). Following 24 h of exposure, crude extracts of all four macroalgal species caused significant coral tissue bleaching and reduction in effective quantum yield. The corals were able to recover within 72 h of the removal of extracts, except those that were exposed to L. challengeriae. While some macroalgal extracts caused an increase in the alpha diversity of coral microbiomes, there were no significant differences in the composition and variability of coral microbiomes between controls and macroalgal extracts at each sampling time point. Nevertheless, DESeq2 differential abundance analyses showed species-specific responses of coral microbiomes. Overall, our findings provide insights on the limited effect of chemically mediated interactions with macroalgae on coral microbiomes and the capacity of corals to recover quickly from the macroalgal chemicals.

Temporal and spatial dynamics of tropical macroalgal contributions to blue carbon.

Blue carbon ecosystems are a vital part of nature-based climate solutions due to their capacity to store and sequester carbon, but often exclude macroalgal beds even though they can form highly productive coastal ecosystems. Recent estimates of macroalgal contributions to global carbon sequestration are derived primarily from temperate kelp forests, while tropical macroalgal carbon stock in living biomass is still unclear. Here, using Singapore as a case study, we integrate field surveys and remote sensing data to estimate living macroalgal carbon stock. Results show that macroalgae in Singapore account for up to 650 Mg C biomass stock, which is greater than the aboveground carbon found in seagrass meadows but lower than that in mangrove forests. Ulva and Sargassum dominate macroalgal assemblages and biomass along the coast, with both genera exhibiting distinct spatio-temporal variation. The annual range of macroalgal biomass carbon is estimated to be 450 Mg C yr-1, or 0.77 Mg C ha-1 yr-1. Noting the uncertainties of the fate of macroalgal biomass carbon, we estimate the potential sequestration rate and find that it is comparable to mature terrestrial ecosystems such as tropical grasslands and temperate forests. This study demonstrates that macroalgal seasonality allows for a consistent amount of biomass carbon to either be exported and eventually sequestered, or harvested for utilization on an annual basis. These findings on macroalgal growth patterns and their considerable contributions to tropical coastal carbon pool add to the growing support for macroalgae to be formally included in blue carbon assessments.

Priorities to inform research on marine plastic pollution in Southeast Asia.

Southeast Asia is considered to have some of the highest levels of marine plastic pollution in the world. It is therefore vitally important to increase our understanding of the impacts and risks of plastic pollution to marine ecosystems and the essential services they provide to support the development of mitigation measures in the region. An interdisciplinary, international network of experts (Australia, Indonesia, Ireland, Malaysia, the Philippines, Singapore, Thailand, the United Kingdom, and Vietnam) set a research agenda for marine plastic pollution in the region, synthesizing current knowledge and highlighting areas for further research in Southeast Asia. Using an inductive method, 21 research questions emerged under five non-predefined key themes, grouping them according to which: (1) characterise marine plastic pollution in Southeast Asia; (2) explore its movement and fate across the region; (3) describe the biological and chemical modifications marine plastic pollution undergoes; (4) detail its environmental, social, and economic impacts; and, finally, (5) target regional policies and possible solutions. Questions relating to these research priority areas highlight the importance of better understanding the fate of marine plastic pollution, its degradation, and the impacts and risks it can generate across communities and different ecosystem services. Knowledge of these aspects will help support actions which currently suffer from transboundary problems, lack of responsibility, and inaction to tackle the issue from its point source in the region. Being profoundly affected by marine plastic pollution, Southeast Asian countries provide an opportunity to test the effectiveness of innovative and socially inclusive changes in marine plastic governance, as well as both high and low-tech solutions, which can offer insights and actionable models to the rest of the world.

Spatio-temporal dynamics of coral-macroalgal interactions and their impacts on coral growth on urbanised reefs.

Interactions between corals and macroalgae are important in influencing benthic community structures on coral reefs and have become increasingly common occurrences. However, little is known about their temporal variation as most studies have only documented them from single surveys. To investigate the dynamics of coral-macroalgal interactions, we surveyed three urbanised reefs in Singapore bi-monthly for three years. We found that the frequency of coral-macroalgal interactions varied greatly across sites and seasons. The extent of coral-macroalgal contact was positively correlated with macroalgal abundance, but the correlation differed significantly among macroalgal genera. The growth rates of Goniopora, Montipora and Pavona corals, but not Platygra, were also negatively correlated with the extent of macroalgal interactions. Overall, our results highlight that coral-macroalgal interactions are spatially and temporally dynamic, with varying effects among coral species. It is critical to consider seasonal fluctuations of macroalgae if the overall long-term impacts of macroalgae are to be understood.

Effects of macroalgae on coral fecundity in a degraded coral reef system.

Global declines in live coral cover and the proliferation of macroalgae on coral reefs is leading to increased coral-macroalgal interactions that impact reef recovery. However, the effects of macroalgae on coral sexual reproduction-a fundamental life-history process for maintaining population abundances-have rarely been quantified. Here, we examined the direct effects of macroalgae contact on the fecundity (eggs mesentery-1) of two coral species, Echinopora lamellosa and Merulina ampliata, across three degraded reefs in Singapore. Increasing macroalgae contact from 5% to 25% significantly reduced fecundity in colonies of both species by 67-82%, and also reduced M. ampliata egg sizes by 11.4%. These results suggest the diversion of energy from reproduction towards other processes such as repair and defence, and also reveal potential differential energy allocation strategies among coral taxa. While corals on Singapore's impacted reefs continue to produce eggs, increasing macroalgae that suppresses coral fecundity may constrain future reef recovery.

Expression of phosphorylated Akt in oral carcinogenesis and its induction by nicotine and alkaline stimulation.

BACKGROUND: In Taiwan, it is well documented that cigarette smoking and areca nut chewing contribute to the risk of oral squamous cell carcinoma (OSCC). The role of phosphorylated Akt (p-Akt) in oral carcinogenesis induced by nicotine and alkaline environments was investigated. METHOD: Immunohistochemistry (IHC) was used to detect p-Akt expression in cancerous (n = 30) precancerous (n = 30), and normal mucosa tissues (n = 10). Western blotting was used to detect time-dependent induction of p-Akt by 100 microM nicotine in normal human bronchial epithelial cell (NHBE), normal human oral keratinocytes (NHOK), immortalized human epithelial cells (HaCaT) and OEC-M1 cells, dose-dependent induction of p-Akt in OEC-M1 and HaCaT cells and pH effect of p-Akt in OEC-M1. The unpaired t-test and the Fisher's exact test were used to analyze the p-Akt immunoreactivity in various groups and its association with clinicopathological parameters. RESULTS: Higher p-Akt expression in cancerous group than in normal mucosa (P = 0.0002) and precancerous (P = 0.0049) groups was observed. A time-dependent increase in p-Akt in the NHBE, NHOK, HaCaT and OEC-M1 cell lines was observed with 100 microM nicotine treatment. The dose-dependent increase in p-Akt by nicotine treatment in HaCaT and OEC-M1 cells was obviously observed. Higher p-Akt expression in more alkaline environment (pH 8.0) was observed than at pH 7.4 in OEC-M1 cells. CONCLUSION: A potential role for increased p-Akt may relate to the dose and time of nicotine use. The potential role of an alkaline environment to enhance nicotine-related oral carcinogenesis may exist.

Allelopathic effects of macroalgae on Pocillopora acuta coral larvae.

Allelopathy has been proposed as a key mechanism mediating coral-algal interactions; however, few studies have tested macroalgal allelochemicals on coral larvae. In this study, we examined the effects of crude extracts from four macroalgal species on Pocillopora acuta larvae under different exposure conditions. Larval mortality increased considerably with increasing concentrations of Bryopsis sp., Endosiphonia horrida, and Lobophora sp. extracts. Increasing E. horrida and Lobophora sp. extract concentrations also substantially decreased larval settlement. No detectable effects on larvae were observed in Hypnea pannosa extracts. Further, while larval mortality increased with exposure duration to Lobophora sp. extracts, larval settlement was enhanced at 12 h exposure, but reduced at shorter and longer durations. Our results emphasize that macroalgal chemical effects are highly dependent on macroalgal species and exposure conditions. On reefs dominated by allelopathic macroalgae, the survivorship and settlement of coral larvae are potentially constrained, thereby limiting the recovery of degraded reefs.

Multimodality treatment for rehabilitation of adult orthodontic patient with complicated dental condition and jaw relation.

A 50-year-old man with severe malocclusion requested comprehensive oral rehabilitation. He presented with retrognathic mandible, anterior deep bite and a gummy smile in the premaxilla, and tenting occlusal plane with severe buccal crossbite of the left maxillary posterior teeth. Inappropriate fixed prostheses spanned the maxilla and the mandible with a class II jaw relationship. A detailed analysis indicated the need for orthodontic treatment, orthognathic surgery, bone graft at the deficient alveolar ridge for implant surgery and a revision of all prostheses. Over a 2-year-period of management, the patient received anterior osteotomy for intrusion of lower anterior teeth, bilateral sagittal splitting osteotomy for mandible advancement and posterior osteotomy for inward upward repositioning of posterior teeth of the left maxilla to correct major jaw deformities. The deficient alveolar ridge in the premaxilla was augmented by autogenous bone graft harvested during the orthognathic surgery. He sequentially had mini-plate and dental implant as anchorage assisting teeth alignment in the mandible. Two 3-fixture-supported implant prostheses were delivered in the premaxilla and the mandible. The improvement in cosmesis, stability and function through treatment and a 2-year clinical follow-up were considered satisfactory.

Use of methylene blue as a diagnostic aid in early detection of oral cancer and precancerous lesions.

We assessed the sensitivity, specificity, and positive and negative predictive value of methylene blue staining in the diagnosis of oral cancer in 58 patients. The sensitivity was 90%, the specificity 69%, positive predictive value 74%, and negative predictive value 87%. Because of the number of false negatives and false positives we recommend that the diagnosis should always be confirmed by histopathological examination of a biopsy specimen. Methylene blue staining may, however, be useful as a screening tool for oral cancer in large, high-risk groups in a similar way to the more expensive toluidine blue.

A method using vestibulo-sulcoplasty combining a split-thickness skin graft and a palatal keratinized mucosa graft for peri-implant tissue secondary to oral cancer surgery.

Twelve patients presented with oral submucosal fibrosis and loss of keratinized gingiva in a compromised vestibule of a severely deficient mandibular edentulous ridge secondary to oral cancer surgery. They received implant rehabilitation with a total of 49 fixtures without major bone graft augmentation. To overcome vestibular compromise, soft tissue management consisting of simultaneous vestibulo-sulcoplasty, split-thickness skin graft (STSG), and palatal keratinized mucosa graft (KMG) was performed as a second stage when healing abutment was transferred to replace the cover screw of the dental implant. Postoperative follow-up of all patients consisted of clinical and radiographic examinations for an average of 4 years, revealing good stability of implant fixtures with a 91.8% success rate and generally healthy peri-implant tissue, the latter with an average sulcus depth of 2.9 +/- 0.6 mm. Satisfactory results were also demonstrated regarding improved morphology of the vestibule, cosmetics, and prosthetic functionality. Vestibulo-sulcoplasty combining STSG and palatal KMG offers a stable and convenient method for rebuilding peri-implant tissue without need for bone grafting in selected patients who have compromised atrophic ridges secondary to cancer surgery.

Comprehensive rehabilitation after severe maxillofacial injury in a cleft patient.

We present here a complex oral rehabilitation procedure for a 19-year-old male patient with an operated cleft lip and palate who suffered motorcycle accident injuries including facial lacerations, and a severe mandible fracture with loss of teeth, gingiva and alveolar bone. His initial skeletal and occlusal relationship made the emergent surgical management extremely difficult. Emergent soft tissue repair and open reduction surgery for the comminuted fracture at the mandible were performed during the intensive care period. A 2-year period of comprehensive procedures including surgical/orthodontic treatment, implant surgery and bone graft and prosthetic restoration for oral and maxillofacial rehabilitation to treat the severely compromised soft and hard tissue status, intermaxillary jaw discrepancy, and severe malocclusion, were sequentially performed. Satisfactory results were observed after a 5-year follow-up.

Analysis of facial skeletal characteristics in patients with chin deviation.

BACKGROUND: This study was undertaken to investigate the facial skeletal features associated with chin deviation. METHODS: Twenty-five patients (14 males and 11 females) diagnosed with chin deviations of more than 2 mm were recruited. Fifteen skeletal landmarks, including median and lateral points, were located on posteroanterior cephalograms. The CG-ANS (crista-galli of the ethmoid-anterior nasal spine) line and the perpendicular line through the CG were used as references. The differences between the distances from paired lateral points to reference lines were examined with intraclass correlation coefficients to analyze the symmetry of facial skeletal tissue. The factors associated with the amount or direction of chin deviation were analyzed by multiple regression analysis or by logistic regression analysis. RESULTS: Seventeen subjects (68%) showed chin deviation to the left side and 8 subjects (32%) to the right side. Sixty-eight percent of subjects presented with Angle Class III malocclusion. Horizontal distances of all paired lateral points to the y-axis, in mandibular body length and effective length, showed a low grade of symmetry. Only vertical distances of paired zygomaticofrontal sutures and zygonion points to the x-axis were asymmetric. However, there were no significant asymmetries of the gonial angle, ramus height, and vertical distances from other paired lateral points to the x-axis. The amount of chin deviation was associated with the absolute differences of the left and right antegonion to the y-axis and zygomaticofrontal suture to the x-axis. The direction of chin deviation was significantly associated with the difference in the effective length of bilateral mandibular halves. CONCLUSION: Facial skeletal asymmetry exists in patients with chin deviation. This should be considered when planning treatment for both the nonsurgical and surgico-orthodontic cases with chin deviation.

Segmental osteotomy to reposition multiple osseointegrated dental implants in the anterior maxilla in a trauma patient.

A 16-year-old young man had severe loss of alveolar bone and lost four teeth in the anterior maxilla because of traumatic injury in a traffic accident. To overcome the surgically compromised condition for implant rehabilitation, the deficient ridge was augmented by autogenous bone graft from the mandibular symphysis. The augmented ridge had much improvement in width but less in vertical height. Four implants were placed to gain initial osseointegration. Segmental osteotomy was performed to occlusally reposition the implants and bone for 5-mm in the anterior maxilla. After 2 years of clinical follow-up, the rehabilitation outcome is satisfactory and stable.